Effects of Microwave Pretreatment of Apple Raw Material on the Nutrients and Antioxidant Activities of Apple Juice

Microwave technology has been widely applied in food processing. To investigate the effects of microwave pretreatment of raw material on the nutrients and antioxidant activities of apple juice, the apple materials were treated with 90, 270, 450, 720, and 900 W microwave at 25, 50, 75, 100, and 125 s, respectively. The results showed that after the raw materials were treated with microwave, the vitamin C, amino nitrogen, and anthocyanin content decreased, and the total flavonoids and polyphenol of apple juice increased. Further, the total polyphenol of apple juice originating from raw material treated with 900 W microwave through 75 s was 115% higher than that of control samples. The antioxidant activities of prepared apple juice increased in terms of diphenyl-picryl hydrazyl, superoxide anion and hydroxyl radical scavenging capacity, reducing power, and iron chelating activity. So appropriate microwave pretreatment of apple raw material could increase some specific nutrients and enhance the antioxidant activities of apple juice